Toroidal roller bearings are known and have been used for many years due to its ability to allow for both axial and angular relative displacement between its bearing rings (outer ring and inner ring). The function and general design of a toroidal roller bearing is for instance described in EP 0175858. The function of the bearing is enabled by the curved construction of the inner and outer rings' raceways which are adapted to conform with the curved shape of the roller elements. Hence, toroidal roller bearings combine self-aligning capability with considerable axial displacement ability.
Due to its capabilities, toroidal roller bearings provide a wide range of applicability in various bearing arrangement designs. In particular the toroidal roller bearings simplify designs comprising e.g. a long shaft that may be subject to temperature variations and bending. Furthermore, the construction of the toroidal roller bearing allows for suitable load distributions as well as low frictional running.
Some concerns when using a toroidal roller bearing have been discovered by the inventors that may arise in different applications. These concerns have been shown to be caused by e.g. the cage in the bearing. Roller elements in the bearing which are in an unloaded zone may be affected by the cage in a negative way. The rollers, when in an unloaded zone, may for instance be braked by the cage, which will lead to roller slip. Roller slip is something that should be avoided because the lubrication film that is needed between the roller elements and the bearing's raceways is disturbed or even vanished when the slip becomes too large. This may lead to a reduction in the service life. Another effect that may arise for the rollers in its unloaded zone is roller skew, caused by e.g. the cage, which may lead to increased friction in the bearing, increased unwanted forces on the cage or increased wear of the bearing components. Yet another effect that may arise for the rollers in its unloaded zone is that the rollers are moved in its axial direction. This may lead to noise and damages on the surfaces of the rollers and the raceways.